This invention relates to pipe installation, and in particular to a device for attachment to a pipe being installed underground and to a method of installing a pipe by the use of such a device. The term pipe is to be construed herein as covering cables as well as tubular pipes.
There are two main ways of installing pipes underground by trenchless methods, namely directional drilling and swage lining. Directional drilling is commonly used to install pipes under areas such as roads, rivers, airport runways or environmentally sensitive sites where it is not appropriate to dig trenches. A rotating drill is used to advance a drill pipe, extendable in sections, so that the drill pipe forms a pilot hole and follows a desired path underground between a launch area and a target area. At the target area, a cutter is attached to the end of the drill pipe. Behind the cutter is a swivel to Which is attached the pipe to be installed. The drill pipe is then pulled back through the pilot hole, the rotating cutter enlarging the pilot hole as it goes. As the drill pipe is pulled back through the pilot hole, the pipe to be installed is pulled through the enlarged hole from the target area to the launch area. Swage lining involves squeezing a plastics pipe between rollers in order temporarily to reduce its diameter and then pulling (by winch and cable) the pre-squeezed pipe through an existing damaged or faulty pipe or through an existing bore.
In both these methods there are two main problems. The first is ensuring that the magnitude of the pulling force applied to the pipe is not excessive and, in particular, that the pulling force does not stretch the pipe beyond its elastic limit. The second is to ensure that a verifiable record is available of the variation of pulling force during the installation process. In tile absence of proper verification, it is possible for data relating to pulling force to be tampered with. The invention aims to solve both of these problems.
According o one aspect of the invention there is provided a device for attachment to a pipe to be installed in the ground, the device having tensile force detector means for detecting a pulling force applied to the pipe as the latter is pulled through the ground, storage means for storing data representative of the detected tensile force, with the stored data being protected against unauthorised access by a security code or procedure, and access means for enabling the data to be subsequently retrieved by use of the security code or procedure. Thus, a device according to the invention not only detects the pulling force but stores it in a way which enables the data to be accessed and verified as being authentic and correct. The attachment of the device to the pipe to be installed may be direct or indirect, the requirement being that the device is subjected to the tensile force applied to the pipe to be installed.
The device preferably has an inclinometer for detecting the inclination of the device as the latter is pulled through the ground, the storage means then additionally storing data representative of the detected inclination, this data also being protected by the security/verification code. The device may have pressure detector means for detecting the pressure surrounding the device as the latter is pulled through the ground, the storage means then additionally storing data representative of the detected pressure, the security/verification code also protecting this data.
The device may be associated with a telemetry system for transmitting the data to the ground surface. For example, the device may have a socket for connection of hard wiring for transmitting the data to the surface. Such a device may have releasable clamping means for clamping the device to one end of a pipe to be installed. Alternatively, the device may have a transmitter for transmitting the data by radio to a receiver outside the device, and the receiver may be on the ground surface but is prefereferably located in the pipe to be installed, the receiver being linked by hard wiring passing through the pipe to an antenna positioned above ground. This antenna may be positioned at or near the reception area where the pipe to be installed is fed into the ground. The antenna mail communication with a receiver positioned at or adjacent the launch area where a drilling rig is employed to pull the drill pipe, the device and the pipe to be installed through the ground.
The access means may be a socket or port on the device, enabling the stored data to be downloaded with verification code, e.g. into a personal computer, after the device is retrieved from the ground. However access to the data is dependent on the security code or procedure being used.
The invention includes within its scope a pipe installation system comprising a device according to the invention in combination with a drilling rig having means for recording data generated during installation of the pipe, the data generated by the drilling rig and the data generated by the device being combined to provide a customer report including the precise route along which the pipe has been laid.
According to another aspect of the invention there is provided a method of installing a pipe underground, comprising using a detector to detect a tensile force applied to the pipe as the latter is pulled through the ground and storing in the detector data representative of the detected pulling force, the stored data being protected against unauthorised access by a security code or procedure, ready for subsequent retrieval of the data by use of the security code or procedure.
The detector may also detect the inclination of the device and store this data representative of the inclination, and may also detect the pressure surrounding the device and store this data, in both cases this further data being protected by the security code or procedure.